Semiconductor memories may be formed and fabricated using various materials, such as silicon oxide (SiO2), noble metals, conductive metal oxide, and others. Conventional fabrication techniques for semiconductor-type memories typically use deposition of thin film materials on substrates (e.g., a silicon wafer), which are subsequently etched away (“etched”) using different types of chemical and/or mechanical etching procedures and etchants. However, conventional techniques may be problematic for some types of memory devices.
Conventionally, a memory cell, including its electrodes and one or more layers of memory material that are positioned between the electrodes are etched as a stack. For example, a set of vertically configured layers of material are formed and etched to provide the memory material(s) that allows for data to be stored or retrieved based on how voltages are applied across the memory material causing a change in conductivity in the memory material that is indicative of stored data (e.g., a plurality of resistive states). However, etching a memory material, such as a layer of conductive metal oxide, may cause degradation of functional properties of the memory material. For example, some memory devices with etched memory material typically experience reduced current flow through the memory cells. There is an inverse relation between the size of a memory cell and the level of degradation of some functional properties of the memory cell. Further, poor fabrication techniques may cause detrimental effects such as a “picture frame effect” where materials can attach to surfaces, resulting in defects that can degrade performance or altogether destroy the electrically conductive properties of a fabricated memory. As a result, device yield is reduced and manufacturing costs are increased. As semiconductor feature size and memory cell size continue to decrease, the degradation of functional properties continues to increase.
There are continuing efforts to improve methods for fabricating memory devices.
Although the previous drawings depict various examples of the invention, the invention is not limited by the depicted examples. Furthermore, the depictions are not necessarily to scale.